The purpose of the work described in this proposal is to continue study of the mechanisms of cellular immunity and hypersensitivity. Our aim is to acquire knowledge of basic mechanisms which can be used to rationally manipulate these cellular processes in certain human clinical conditions where enhancement of cellular immunity might lead to prevention or alleviation of disease such as infections or neoplasia, or where suppression might diminish tissue injury caused by cellular hypersensitivity. The proposed investigation is a direct outgrowth of our interests in the interaction of lymphocytes, their mediators and macrophages in cellular immunity. Studies in this project will include further characterization of the macrophage glycolipid which appears to act as a receptor for the lymphocyte mediator, migration inhibitory factor (MIF), including its chemical structure and function; further characterization and purification of guinea pig and human MIF; further studies on an MIF enhancing factor obtained from cell membranes; and further studies on the mechanism of macrophage activation, with an emphasis on membrane changes. The mechanisms of collagen induced arthritis, which has been shown to be a cell mediated immune reaction, will be further studied focussing on immunologic ways to suppress it.